Chest radiography is one of the most important x-ray examinations. Up to one-half of all radiograms taken are chest films. In spite of recent advances, such as CT scanning, the chest radiograph remains the most important screening test to rule out lung disease. The detectability of early disease depends largely on the experience of the radiologist and on technical factors. We propose to construct a novel apparatus which uses moving slots, virtually removing all the scatter, even if higher kilovoltage technique is used. A set of primary and secondary slots will travel over a 14 inch distance in approximately one-half second. Every 0.5 cm. increment will be exposed for 1/120th of a second. Therefore, motion unsharpness and kymographic effect will be negligible. A uniform radiographic density will be assured by the use of a ripple-free, three-phase generator. The efficacy of this new device will be tested on phantoms and cadaver chests. Some cadavers will have nodules attached to the chest wall. Three experienced radiologists will interpret these radiographs. A comparison will be made with standard high kV radiography.